This application relates to arrangements for cooling a gas turbine engine turbine section utilizing multiple sources for the cooling air.
Gas turbine engines are known and typically include a fan delivering air into a bypass duct as propulsion air, and into a compressor as core airflow. The air is compressed in the compressor and delivered into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors driving them to rotate. The turbine rotors, in turn, drive the fan and compressor rotors.
As can be appreciated, the turbine section experiences very high temperatures. Thus, it is known to provide cooling air from other locations in the gas turbine engine to cool the turbine section.
It is known to tap cooling air from a downstream location in the compressor section to the turbine sections. The downstream compressor air is hot itself. Thus, it is known to pass the cooling air through a heat exchanger on the way to cooling the turbine sections.
Particularly at upstream turbine rotor stages, this high pressure compressed air is able to provide adequate cooling.